Project summary In spite of the major advances in the development of effective anti-HIV drugs, currently some 2 million new infections still occur annually worldwide and over 95% via heterosexual contact. While prevention measures have made progress, such as PrEP, these measures are frequently either ignored, misused, or often non- negotiable for the female partner. Thus, providing choices for prevention of infection that are female controlled will be an asset in the fight to curb the rate of new infections worldwide. With the recent explosion of broadly neutralizing antibodies (bnAbs) from HIV infected patients, several have been used to demonstrate prevention of virus acquisition, even when administered post exposure. Unfortunately, vaccines have so far fallen short of inducing bnAbs, and though topically delivered bnAbs have shown protection, such protection has to date shown limited durability. To that end, a novel approach for expressing antibodies, with surprisingly long kinetics, in the female reproductive tract (FRT) via synthetic mRNA was recently demonstrated. Delivery was achieved through direct, rapid, aerosol exposure of the FRT epithelium to naked mRNA in water. Persistence of the antibody was achieved through the incorporation of a GPI-linker into the heavy chain. In rhesus macaques, the ability to protect macaque FRT explants from SHIV infection ex vivo has been shown. The long-term goal is to develop a cost-effective mRNA-based approach for expressing bnAbs in the FRT, providing a new paradigm for generating anti-infection barriers at the mucosal port(s) of entry. The short-term goals are to optimize the delivery, longevity and protective efficacy of bnAbs against SHIV infections of rhesus macaques by: 1) optimizing the delivery approach and protocol such that we have efficient transfection of the vaginal and cervical epithelium, 2) optimization of the antibody linker strategy to promote long-term expression in macaques, and 3) testing of single antibodies and combinations, including bi-specific antibodies. The efficacy of the optimization will be tested in a true challenge study in the macaque model. If successful, design information vital for making a proper device for delivering mRNA to the FRT in humans will be provided, and sufficient pre-clinical data in support of a future FDA IND application.

Narrative While prevention measures for HIV have made significant progress, such as PrEP, these measures are often either ignored, misused, or non-negotiable for the female partner; therefore, there is a clear need world-wide for new approaches for the prevention HIV infections that are female controlled. In this application we plan to develop a synthetic mRNA-based approach for the delivery of broadly neutralizing antibodies against HIV to the female reproductive tract (FRT) through direct, rapid, aerosol exposure of the FRT epithelium to naked mRNA in water, and when combined with antibody engineering, should allow for rapid expression, and controllable persistence of the protective antibodies in tissues and secretions. Overall this approach represents a new paradigm for HIV prevention, one that can be extended and combined with the co-expression of other anti-sexually transmitted infection antibodies, such as those against HSV-2.